94 rodeo v6 stuttering problems

[nickpapa]

thank you trooperbc i will definitely do those random tries that the focus guy did.

i was trying to think out of the box as well and was thinking MAYBE the clip is not totally in on the o2 sensor and when its hot, it runs like crap because its not reading anything, and when i put it in reverse, since the front dips down, it pushes the clip together making contact and the o2 starts functioning again? its a long shot but i guess ill just have to take a look today.

[nickpapa]

ok here are the updates from today.

replaced the o2 sensor and nothing changed. i then figure out which egr valve i should have cleaned and cleaned it with some carb cleaner. still nothing change.

i then tried the "take every fuse out" idea and nothing changed again. looked for hitch wires but it doesnt even have a hitch. what i am 300% sure about is that it will ONLY act like this in all gears that go forward (D, 2, 3). in reverse it will drive great with no problems whatsoever. if only it was legal to drive in reverse everywhere we'd be all set.

i also disconnected the battery for a couple minutes thinking maybe it will reset itself or something but nothing changed again.

this thing is driving me nuts. but what i am totally sure is that it will only act like this in gears that move forward when the car is hot. when its cold its drivable. still stutters at idle (in D), but it will get you where you need to go. once it warms up though its a mess.

So now we've crossed out:

o2 sensor
PCV valve
spark plugs
vacuum lines
fuel filter
fuse trick

not sure where to go from here

[trooperbc]

ok...i take it one of the fuses you removed is for the backup light....

now, disconnect the mode switch, follow the wires to the switch. i believe your connector is right there up from the switch. drive it manually (the electronics won't work). see if that gets you any change.

//bc

[nickpapa]

i will do that trooperbc. just one question, where is the mode switch located? is it on the trans itself or under the center console?

by the way, i removed every fuse in the dash, and all the fuses in the engine bay that were for any type of accessory.

[trooperbc]

the mode switch is around the gearselector shaft on the left(driver's) side of the transmission where the linkage from the shifter attaches. (the bmw has the switch up at the shifter, btw).

//bc

[nickpapa]

so i think i found the mode switch. its the part that kinda looks like a slice of pizza connected directly to the linkage?

well if so, i tried following the wires and it looks like they go up along the side of the radiator fan (drivers side). from there i cant see where it goes. i took the front portion of the airbox out and saw 2 clips going to the headlights and one that was part of the main harness. i took the connector off that was part of the main harness, and the car wouldn't start. any idea exactly where the connector is for the mode switch?

[trooperbc]

Originally Posted by nickpapa

so i think i found the mode switch. its the part that kinda looks like a slice of pizza connected directly to the linkage?

well if so, i tried following the wires and it looks like they go up along the side of the radiator fan (drivers side). from there i cant see where it goes. i took the front portion of the airbox out and saw 2 clips going to the headlights and one that was part of the main harness. i took the connector off that was part of the main harness, and the car wouldn't start. any idea exactly where the connector is for the mode switch?

this illustration is from the isuzu online parts site www.myisuzuparts.com a good resource especially if you don't have the factory manual(s) from www.helminc.com very pricey but excellent overall.



#61 is the switch (with wire and connector); #102 is the metal cover that you see. different models and years have different length wire looms so the connector is in different places. on my 1992 trooper it has a very long loom that ends in the connector under the air cleaner box, clipped into the front tin behind the headlights, there are 3 connectors, the modeswitch connector is the bottom one and i had to remove the other two first (of course!). to get to it i had to remove the aircleaner box topandbottom. others have a short loom with the connection right at the trans up from the switch.
//bc

[nickpapa]

ok so from the pic it looks like i definitley found the correct part. ill have to take another look at it tonight when i get home from work.

it sounds like mine is long like your troopers and goes up to the same spot. i will have to take another look today and try to find it. maybe ill remove the whole airbox like you did instead of just the front portion. but i also had to take off the 2 clips for the headlights to get to the third clip that i thought was for the mode switch.

ill keep you updated.

[nickpapa]

ok have some updates.

i found the correct clip, unclipped it and again nothing changed. reverses no problem, gets really bad once the car is hot.

any other ideas?

im thinking maybe there is an issue with the ecu? but then why would it only do it once it is warm? i just dont get it

[FL 3.2L]

Scan it for codes.

[nickpapa]

will it blink codes even if the engine light isnt on?

[FL 3.2L]

I forgot that you are OBDI. I'm OBDII and I think I can get codes without a CEL.

[trooperbc]

Originally Posted by nickpapa

ok have some updates.

i found the correct clip, unclipped it and again nothing changed. reverses no problem, gets really bad once the car is hot.

any other ideas?

im thinking maybe there is an issue with the ecu? but then why would it only do it once it is warm? i just dont get it

well there are a number of possibilities that rear their ugly heads when warm but not cold

BUT -- THEY DON'T ONLY DO IT IN FORWARD GEARS AND STOP WHEN PUT IN REVERSE.

some of those temp related issues include egr system, 02 system, and the CTS coolant temperature sensor (which is what tells the computer what temp the coolant temp is (different from switch that operates the dash temp gauge), and the temp switch for the intake manifold air.

when cold, the computer operates from predetermined values, then when things are warmed up, it accepts values from the 02 sensor, and allows the egr system to operate.

there is also the issue of the intake manifold gasket, but that is usually an issue on later years.

these things above, 02 sensor circuit, egr system, etc would have been suggested long ago by multiple replies IF your sysmptoms didn't go away depending on gear selection. but maybe you'd better start down those tracks.

will it blink codes even if the engine light isnt on?

yes, codes are stored. obdI is not as precise or prolific in results as obdII diagnostics of 1996 and on. on the other hand, you can read your own codes simply by jumpering a connector and counting the flashes of the CEL. do you know how to do that?

//bc

[nickpapa]

yeah i think i remember reading on here how to do that. i will search again about it just to be safe.

as for egr system and o2, i cleaned the egr, and replaced the o2. i also disconnected the o2 to see if there would be any change but nothing changed. so maybe the ecu is the culprit?

does this year have a dedicated ecu i can take a look at? if so can you tell me where it is?

i remember working on a vw passat once and it was throwing all kinds of codes that were very random. it turned out anti-freeze somehow ended up into the ecu area and was causing all of these wierd issues. cleaned it up and it was fine. not saying this could be the problem but maybe something similar?

UPDATE: so i took a look at the ecu. didn't see anything unusual with the wires or anything so i thought i'd try and check the codes. As per a thread that I found on here, there should be an unused 3 prong connector right by the ecu. well i could not find that 3 prong connector and could only find 3 unused connectors. 1 connector was 2 prong with 2 wires coming out of it, the other was 2 prong with 4 wires coming out of it, and the last one was 1 prong with 1 wire. here are some pics, is one of these the ones i am supposed to test with?